lightwave

Lightwave, or light wave, is a wave of electromagnetic radiation within or near the visible spectrum. Like other electromagnetic waves, a lightwave consists of oscillating electric and magnetic fields that propagate through space at the speed of light. In vacuum, the phase velocity is c ≈ 299,792 km/s, and the frequency f and wavelength λ satisfy c = fλ. In a medium, light slows down by a factor 1/n where n is the refractive index, and its wavelength shortens accordingly, though frequency remains constant.

Light waves can be described as transverse waves, with polarization describing the orientation of the electric field. They exhibit interference and diffraction, enabling phenomena such as fringes and imaging through lenses and gratings. The energy carried by light can be quantized in photons, each with energy E = hf and momentum p = h/λ; the wave and particle pictures are complementary.

The visible portion of the spectrum is roughly 380 to 750 nanometers, but the broader electromagnetic spectrum includes infrared, ultraviolet, and beyond. Lightwaves underpin a wide range of technologies, including imaging, spectroscopy, and communications, especially fiber optics that transmit light signals with minimal loss. The behavior of light in materials is described by laws such as Snell's law for refraction and Fresnel equations for reflection and transmission at boundaries.

Historical development began with Maxwell's equations, which showed that changing electric and magnetic fields propagate as electromagnetic waves, with the speed of light determined by fundamental constants.